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Rosenblat M.,Rappaport Family Institute for Research in the Medical science | Aviram M.,Rappaport Family Institute for Research in the Medical science | Aviram M.,Lipid Research Laboratory
Annals of Nutrition and Metabolism | Year: 2011

Background/Aims: To analyze the effects of pomegranate juice (PJ) and punicalagin on macrophage triglyceride metabolism. Methods: Triglyceride metabolism was analyzed in PJ- or punicalagin-treated J774A.1 macrophages or in mouse peritoneal macrophages (MPM) harvested from C57BL/6 mice or from paraoxonase 2 (PON2)-deficient mice. Results: PJ (0-50 μM) significantly and dose-dependently decreased the triglyceride content and triglyceride biosynthesis rate in J774A.1 macrophages or in C57BL/6 MPM by about 30%. Similarly, punicalagin, the major PJ polyphenol, inhibited the MPM triglyceride biosynthesis rate by 40%. The triglyceride hydrolytic rate, however, was not significantly affected by PJ or punicalagin. The activity of diacylglycerol acyltransferase 1 (DGAT1; the rate-limiting enzyme in triglyceride biosynthesis) was significantly inhibited, by 54%, in C57BL/6 MPM that were treated with 50 μM PJ or punicalagin, with no significant effect on DGAT1 mRNA or protein expression. Both PJ and punicalagin increased (1.7-fold) MPM PON2 mRNA expression, and PON2 was previously shown to inhibit DGAT1 activity. However, the addition of PJ or punicalagin (50 μM) to microsomes from PON2-deficient MPM still resulted in a significant reduction (50-58%) in DGAT1 activity. Conclusions: We conclude that the inhibitory effect of PJ on triglyceride biosynthesis could be attributed to a direct effect of PJ on DGAT1 activity. Copyright © 2011 S. Karger AG, Basel. Source

Haber A.,Technion - Israel Institute of Technology | Abu-Younis Ali A.,Technion - Israel Institute of Technology | Aviram M.,Lipid Research Laboratory | Gross Z.,Technion - Israel Institute of Technology
Chemical Communications | Year: 2013

The corrole-based catalytic antioxidant 1-Fe reduced the cholesterol biosynthesis ability of macrophages, harvested from mice treated with it. 1-Fe and a non-redox active analogue of it affect the committed step of the biosynthetic pathway-the HMG-CoA reductase catalysed reaction-by acting as allosteric inhibitors of this key enzyme. This journal is © The Royal Society of Chemistry 2013.. Source

Kaplan M.,Medical science and Rambam Medical Center | Aviram M.,Lipid Research Laboratory | Hayek T.,Lipid Research Laboratory
Pharmacology and Therapeutics | Year: 2012

Diabetes mellitus (DM) and hyperglycemia are associated with premature and accelerated atherosclerosis. This is mediated by induction of vascular dysfunction, increased inflammatory burden and increased lipid peroxidation, all leading to enhanced macrophage foam cell formation. In DM, low density lipoprotein (LDL) oxidation by macrophages is increased due to the activation of several pro-oxidant systems, as well as the depletion of antioxidants, such as the paraoxonases (PONs). Paraoxonases protect against atherogenesis, as serum PON1 exerts a protective role against DM development by stimulating insulin secretion from β cells, and its unique antioxidant properties. Oral supplementation of insulin to mice significantly attenuates macrophage foam cell formation, reduces oxidative stress and decreases the atherosclerotic plaque area and. Insulin may directly inhibit lipid peroxidation via inhibition of NADPH oxidase expression. Insulin has additional protective effects against DM-induced macrophage cholesterol accumulation by inhibiting CD36 expression (an oxidized LDL receptor), and by inhibiting HMGCoA reductase expression (the rate limiting enzyme in cholesterol biosynthesis), through inhibition of the formation of active SREBP-1 (the transcription factor that activates HMGCoA reductase). Although insulin is mainly an anti-atherogenic agent, it also has some pro-atherosclerotic effects in insulin resistant individuals including the induction of dyslipidemia, cellular triglycerides accumulation and pro-thrombotic effects. This review's intent is to help clarify the mechanisms underlying the protective anti-atherogenic role of insulin in DM as well as some pro-atherogenic effects. A better understanding of insulin's involvement in the pathogenesis of atherosclerosis in DM could have major therapeutic implications for DM treatment and its consequent cardiovascular complications. © 2012 Elsevier Inc. Source

Nagata T.,Lipid Research Laboratory | Redman R.S.,Oral Pathology Research Laboratory | Lakshman R.,Lipid Research Laboratory | Lakshman R.,George Washington University
Analytical Biochemistry | Year: 2010

Current methods of nuclear isolation from liver disrupt the plasmalemmae via homogenization and separation of the nuclei by high centrifugal force (HCF) through gradients of sucrose or other substances for up to 80. min. The use of HCF for such a long time increases the potential for nuclear damage and degradation by endogenous proteases. We compared four combinations of alterations to classical nuclear isolation methods as follows. Mouse liver was gently crushed through a fine mesh with and without in vivo perfusion with collagenase. The cell suspension was centrifuged at 600. g to remove gross debris and then at moderate centrifugal force (MCF, 16,000. g) or high centrifugal force (HCF, 70,000. g) through sucrose gradients for 30. min. The purity of the isolated nuclei was assessed biologically and morphologically, including analyses of representative marker proteins for nuclei and cytoplasm. The results indicate that MCF and no collagenase provided the highest nuclear integrity and purity, whereas MCF with collagenase is a viable option if priority is given to yield. The method is especially suited for small samples and so should facilitate studies with human liver biopsies and livers from mice, the most widely used species for gene targeting. © 2009 Elsevier Inc. Source

Paland N.,Lipid Research Laboratory | Aharoni S.,Lipid Research Laboratory | Fuhrman B.,Lipid Research Laboratory
Atherosclerosis | Year: 2013

Objective: Monocyte-to-macrophage differentiation and macrophage death play a pivotal role in atherogenesis. uPA and its receptor uPAR are expressed in atherosclerotic lesion macrophages and contribute to atherosclerosis progression. In the present study we investigated the effect and mechanisms of action of uPA on monocyte-to-macrophage differentiation and on macrophage apoptotic death. Methods and results: The number of mouse peritoneal macrophages (MPM) harvested from uPAR-deficient (uPAR-/-) mice was significantly lower by 30% in comparison to control C57BL/6 mice. Invitro, uPA intensified PMA-induced THP-1 monocyte differentiation, as determined by increased expression of the macrophage marker CD36. This effect was mediated via G1 arrest, downregulation of G2/S phase and inhibition of PMA-induced cell death. uPA attenuated MonoMac6 (MM6) macrophage-like cell line apoptosis induced by oxidized LDL (Ox-LDL) and by thapsigargin(inhibitor of sarco-endoplasmic reticulum Ca2+-ATPase), but not by staurosporine(protein kinase inhibitor), suggesting that uPA antiapoptotic activity is Ca2+-independent, but involves a kinase activation. The antiapoptotic activity of uPA was dependent on the presence of uPAR, and it involved ERK1/2 activation-dependent downregulation of the proapoptotic protein Bim in macrophages stimulated with Ox-LDL. Conclusions: The present study demonstrates, for the first time, that uPA stimulates the differentiation of monocytes into macrophages and attenuates Ox-LDL-induced macrophage apoptotic death via ERK1/2 activation-dependent Bim downregulation. These processes may result in prolonged macrophage survival in the lesion, increased lesion cellularity, and eventually necrosis, which accelerates lesion development. © 2013 Elsevier Ireland Ltd. Source

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